Two-way-repeater circuits.



rammed July 9, 1918.

8 SHEETS-SHEET l.

M. M. DOLMAGE.

TWO-WAY REPEATEH CIRCUITS. APPucAlon min nov. a. me.

OW LII W/TNESSES M. M. DOLMAGE TWO-WAY REPEATER CIRCUITS.

APPLICATION FILED noms. 191s.

8 SHEETS-SHEET 2.

$1,272,022, Patented July 9, 1918.

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Two-WAY REPEATER cmcuns.

APPLICATION FILED NOV. 8. ISIS.

Patented July 9, 1918.

8 SHEETS-SHEET 4.

iiiiii iiiiii INVENTOR M. M. DOLM-AGE.

TWO-WAY B EPEATER CIRCUITS. APPucATloN msn nov. s. 191s.

PatentedJuly 9, 1918.

a sains-SHEET s.

l I AMAA;

VVIIIU' W/TNESSES.'

, TJ. 42" f M. MQ noLMA-GE.

TWO-WAY REPEATEB CIRCUITS.

APPLlcATloN FILED Nov. 8.4mm

1 ,272,022. Patented July 9, 1918.

8 SHEETS-SHEET 6.

AAAAAA Fig@ . C 2 WITTNESS YfS 9 M. M. DOLMAGE.

TWO-WAY REPEATER CIRCUITS'.

APPLICATION FILED4 NOV. 8. |916.

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` M. M. DOLMAGE.

TWO-WAY REPEATER CIRCUITS.

APPLICATION FILED noma. |916.

Patented July 9, 1918.

B SHEETS-SHEET 8.

' C Wittnessee: n

IIV VEN TOR MIHRAN M. DOLMAGE, OF WASHINGTON, DISTRICT OF COLUMBIA'.

rwo-wAY-REPEATER CIRCUITS.

Specification of Letters Patent.

Patented Jury a, isis.

Continuation in part of applications Serial Nos; 30,664, 30,665, 30,666, and 30,667, filed May 26, 1915. `This application 1ed November 8, 1916. Serial No. 130,303.

To all whom t may concern.' l Be it known that I, MIHRAN M. DOLMAGE, a citizen of the UnitedStates, residing at Washington, District'of Columbia, have invented certain Improvements in Connection. with Two-Way-Repeater Circuits, of which the following description, in connection with accompanying drawings, is a specification.

This invention has for its object the amplilcation and transmission of'speech cur rents in both directions. It utilizes for this purpose voice operated circuit changing means, so as to prevent the soicalled singing. of the vtwo-way-repeater system, by controlling the circuits of this system and establishing them accurately with reference to the desired direction at speech transmission. Circuit changing means, voice controlled in theirl operation, have `heretofore been used. This invention diii'ers however from previous inventions in that it does not require the operation of a switch, voice controlled or otherwise, for puttingf into communication the two terminating telephone stations. In the system described herein the terminating stations are normally connected together through the two-way repeater circuit, which repeater circuit is inV normally full repeating relation in both directions.

A further important advantage of the system described herein consists in the utili.- zation 'of devices for amplifying the voice currents so that the control of the circuitV .changlng means by the voice currents, may.

be made certain and practically operative. The use of such amplifying devices has been indicated in conjunction with the par ticular two-way repeater circuit shown in attached drawings, but it is clear that such devices may be used with any other two-way repeater circuits which. require for their proper operation the utilization of `voice operated circuit changing means. A practical solution is shown in theutilization of a device of the typeknown as an audiom which canL be made to amplify alternating currents of voice 'frequencies and convert these currents into direct current. becomes possible 4to use direct current electromagnetic relays, which usually can be made more sensitive than electromagnetic alternating current relays, for the purposeJ of securing the proper repeating relations 1n both directions.

with the two-way repeater circuit.

It then frequencies into direct current, associatedL with direct current electromagnetic control relays. yF ig. 4,- shows a different association of the automatic control relay circuits Fig. 5, shows a different association of the receiving circuits of the two one-Way repeaters from that shown in Fig. l, Fig. 2, Fig. 3, and

. Fig. 4. Fig. 6, shows the same arrangement for the receiving circuit of the two one-way repeaters as shown in Fig. 5, but a different association of the automatic controlv relay circuits in the two-way repeater circuit. Fig. 7, shows a third modification in the association of the receiving circuits of the two one-way repeaters and of the automatic control circuits which are wired as diagonals of bridge arrangements.y Fig. 8, shows asimilar arrangement to that shown on Fig. 7, except for the difference in the combination of the secondary windings of the receiving circuits. In Fig. 9, the receiving circuits of the two one-way repeaters are still shown'as'in Fig. 7, but the secondary windings of the automatic control relay circuits are differently combined. In Fig. 10, the arrangement is similar to that shown in Fig. 8, but is different in the association of the automatic control, circuits. Fig. 11, shows a still different association of theautomatic control relay circuits with the receiving circuits in the Wheatstone bridge arrangements. Fig. 12, shows the same arrangement for the automatic control circuits as in Fig. 11, but differs from this ligure in the arrangement, in parallel, of the receiving circuits of the two one-way repeaters, instead of the series arrangement shown in Fig. 1l. Fig. 13, shows a circuit arrangement similar to that shown on Fig.` 11, but different in the association of the secondary windings of the automatic control circuits from that shown on Fig. 11. l

Referring first to Fig. 1, of the drawings, G and I-I, are the ends of two subscriber, trunk,- or toll lines between which is in- I G to H. Repeaters A, and A2 may beany stalled the two-way repeating equipment.

- A1 and A2 represent diagrammatically oneway repeaters. Repeater A'1 is arranged for repeating 'speech currents traveling in the direction from H to G and repeater for repeating in the opposite direction, viz.,

repeaters known to the vart. For reasons of convenience in graphical representationy electromagnetic -,type repeaters `of ordinary construction, consist-ing ineach case of an electromagnet, operating a microphone,have

been shown. Line-H connects through primary windings 5vl and 6 and secondary windings 7 and 8 of receiving circuit ofl repeater A1', to the energizing portion of repeater A1. The reinforcing portion or transmitting circuit ofthe same repeater i's connected in a bridge arrangement, being wired as one` arm of the bridge in series with one primary winding 12 of automatic control relay circuit DI. Balancing repeater circuit B1 represents another arm of the bridge and 11 and 12, connect in series with each other is wired in a series with Va second primary winding, winding 11 Aof automatic control relay circuit D2. Line G is Wired as a diagonal of this bridge between the junction points of windings 11 and 12 and the junction points of the reinforcing portion of re-` peater A1 and its balancing electrical circuit Bl. The energizing vportion of repeater A2 is connected inductively through secondary windings 17 and 18 and primary windings 15 and 16 of a second transformer or a receiving circuit across line G in series 4with the bridge arranvement above deb b scribed. The reinforcing portion of this same repeater, repeater A2 is connected in a second bridge arrangement, being wired as one arm of this bridge in series with a primary winding, winding 2 of automatic 'control relay circuit D2.' Balancing repeater circuit B2 represents another arm of this Ysaine bridge and is wired in series with a second primary winding, winding 1, of automatic control relayv circuit D2. Line Hy is wired as a main diagonal of the bridge between the junction points of windings 1 and 2 and junction points of the reinforcing portion of repeater A2 and its .balancing electrical circuit B2Q ri'lhis second bridge arrangement, just described, is wired across line H in series with a' transformer or receiving circuit, already referred to, which connects vinductively through its primary windings 5 and 6 and secondary windings 7 and 8, the energizing portion of repeater A1 with line H. To complete.thedescription of the circuit ar- -rangement shown on Fig. 1, secondary windings 13 and 14 of automatic control relay circuit Dl-associated with primary windings and with automatic control relay C1. Likewise, secondary windings 3 and 4, of automatic controlrelay circuit D2, respectively associated` ininductive relation with primary windings 1 and 2, connect in series with each other and with automatic control relay C2. Contact 9, cont-rolled by this same relay has been shown as arranged to short circuit the energizing portion of repeater A1. Contact 10 of automatic control relay C1 has been shown as arrangedto short circuit the energizing portion of repeater A2. The typical feature ofv the arrangement shown in Fig. 1 consists in the use-of the two bridge`arrangements which have been described in detail. 1t is proposed to design the various component parts of the two bridge arrangements so that for incoming non-amplified speech currents,

reaching the two-way repeater circuit by line G, the electromotive forcesv induced in the two Secondary windings 13 and 14 of automatic control relay circuit D, will be vequal in amplitude and opposite in direction, will neutralize each other, no resultant I current therefore flowing through` automatic relay C1. ASuch a result will be secured'if the impedances of primary windings 11 and 12 are properly proportioned to the mutual impedance between the same'windings and secondary windings 13v and14', respectively. The above necessary and sucient relation may be expressed in a more concrete manner by the formula. Y

As a specific case for a balanced condition, we may make A Zi I Z2 @Mi :PM2

To satisfy the relation as expressed by the above formula it will be preferable to use for the balancing electrical 'circuit B1, a repeater B of the exact type and characteristics as repeater A2, as in such -a case the balancing may be made very accurate.

1n 'the same manner for incoming nonamplified speech currents reaching the two'- way repeater circuit via line H, the elecspeech frequencies have been amplified, by.

repeater A1, for instance, and are traveling toward line G, assho'wn in Fig. 1, the electromotive forces induced in windings 13 and 14 of automatic control relay circuit D1, on account of the iiow of the amplied alternating currents through primary windings 11 and 12, will be in the same direction, will reinforce each other, and result in producing a flow of current through control relay C1. iFor reasons of symmetry the alternating currents of speech frequency, amplified by repeaterA2 and traveling toward line H, will result finally inproducing a iow of current through control` relay C2. It is proposedto have relays C1 and` C2 made sufiiciently sensitive to respond to the amplified voice currents.

In a system, described above in detail, the following operation will obtain: When the comparativelyv weak or attenuated speech currents reach the two-way repeater circuit vialine G, repeater A2 will be energized through primary windings -15 and 16 and secondary windings 17 and 18 of the transformer or receiving circuit associated with this line. .Furtherm'o're, `aportion of `these attenuated currents will How through windings 11 and 12 of automatic control relay circuit D2, through the reinforcing or transmitting portion of repeater A1 and balancing repeater or circuit B1. In view of the special, design of the parts just mentionedI which are associated together in. a

bridge arrangement, the electromotive forces induced in windings 13 and 14 will be equal in amplitude and opposite in direction. There 'will be no current How in windings of relay C1, which will consequently remain in its non-operated normal position. Repeater A2 has, however, been energized as mentioned, and will impress an electromotive force through its reinforcing portion or transmittingvcircuit upon one arm of the bridge arrangement which is in series with primary winding2 of automatic control relay .circuit D2. It will also impress anelectromotive force. upon primary winding 1 of circuit D2,`balancing circuit B2, line H- and also upon the ener; gizing portion of repeater A1 through-"pri- G and H a reactive noise. It will not op- 'y erate as the flow of voice currents in primary windings 1 and 2 will induce two electromotive forces in windings 3 and 4 which are in the same direction. There kwill be, therefore, a current flow in control relay, C2. This relay will operate vand through contacts 9 it controls short circuit of the energizing portion of repeater A1 and render this repeater inoperative. f

The operation of the circuit, illustrated on Fig. 1, for speech currents reaching the two-way repeater circuit 'vialine connection H will be exactly similar to the operation .just described for speech currents reaching the two-way repeater circuit via line connection Gr.l This is clearly evident since the two-way repeater circuit arrangement shown yon Fig. 1 is a symmetrical arrangement.

On Fig. 1, control relays C1 and C2 have .been shown as short circuiting the energizing portions of repeaters A2 and A1, respectively. Instead of this arrangement, the contacts controlled by relay C2 could be arranged equally as well to open circuit the connection between. the energizing portion of repeater A, and windings 7 and 8 of the transformer associated with line H, and the contact controlled by relay C, to open circuit the connection between the energizing portion of repeater A2 and windings 17 and y18 of theytransformer associated .with line G. The modification referred to, or equally evident modifications have not been indicated in the drawings, as it has beenconsidered sufficient to illustrate only one way of securing the result aimed at, lviz., rendering inoperative repeater A1 on speech currents traveling in the direction from line `Gr to line H and rendering inoperative repeater A2 on speech currents traveling in the direction from line H to line G.

To make the operation of control relay C1 and C2 more certain and the design of relaysl C1 and C2 more practical, I'associate these with devices for amplifying alternating currents of speech'frequencies. An audion, such as described in a number of U. S. A. patents (U. S. A. Patent 1,128,292 to E. H.) Colpitts, &c.), which would have its en- `v\ergizing portion wired in series with the secondary windings of either automatic control relaycircuits D1 or D2 audits-reinand amplify, the 1 alternating currents of speech frequencies into unidirectional current, very convenient and practical. Fig. 3 illustrates one method of accomplishing this p result in a very effective manner, by means vof an audion arranged, through the use of a properly poled third battery, wired between the grid and filament elements of the audiom to convert and amplify voice currents into direct or unidirectional currents. H. de F. Arnoldhas vdisclosed-'in.`U. S. A. Patent l,l28,280 lthe association of parts required to accomplish the result mentioned. No detail description of the Ptheory ofthe arrangement is'therefore needed in connec-y tion with this specification. To carry out the Varrangement referred to above into -fetl`ect,

windings 3 and 4 of automatic relay circuit.

D2 are wired in series between the grid and filament elements of the audiom in series with a battery havingits negative pole convnected to the grid. The potential 'of the 35.

third battery required .is determined by lthe actual type of audion bulb used. Di-

, rect current electromagnetic relay F2, which replaces relay C2 of automatic control relay circuit D2, is wired in the circuit between the llilament and plate elements of the audion With this arrangement there is a steady flow of direct or unidirectional current-through relay F2. In order to prevent the operationof relay F2 by this current, I wire across the terminals of this relay a y battery through an adjustable resistance.

This battery is so poled as to tend to neutralize the effect of' the steady current due to the main battery wired between the plate and filament elements of the audion upon relay F2 as shown. By adjusting the variable resistance in series with this auxiliary battery, it is possible to ei'ect a complete neutralization. TJnder these' conditions, and with no flow of alternating currents in the circuit .of the secondary windings 3 and l 'of circuit D2, there will be no flow whatever of current through 'windings of relay F2, which will remain unoperated. However, when the voice currents ampliied by repeater A2 flow through windings l and 2 of circuit D2 toward line H, then there will be an alternating current electromotive force impressed between the4 grid and filament elements of the audion A flow of unidireccuit D2, instead of being wired in series with to secondary winding 4e, and the impedance l `of the reinforcing portion of. repeater A2 is tional current, due to the converted and4 amplitied voice currentsiwill result in windings of relay F2. Relay F2 will operate, and through contact 9 it controls, render inop-- erative repeater A1. ln a similar manner alternating current relay C1 of Fig. l, may be replaced with the combination of direct current relay and a device for converting and amplifying alternating currents into unidirectional currents. i

rlhe drawings 4 to 13, indicate certain modilications in the association of the v'various parts ot the two-way repeater circuit shown in Fig. 1, the fundamental underlying ideas remaining however the same. Fig. e, 8.0 corresponds to only one-half of thecircuit shown on Fig. l, the omitted part being entirely symmetrical. ln this ligure the secondary windings of automatic control cireach other and with control relay C2 are wired in parallel with each other and' with relay C2. In this casethe general relation indicated .for securing 'a balance inthe bridgel arrangement of Fig. l will not hold. rlhe balance will be obtained, however, when primary winding l is equal inevery respect to primary winding 2, secondary winding is equal in every respect made equal to the impedance of the bahl ancing electrical circuit orrepeater B2.

Fig. 5 shows for onefhalf of the circuit of Fig. 1, the omitted partbeing entirely sym- 100 metrical in construction,.the transformer associated with line H wired directly` across line H, in parallel with the bridge arrangement involving automatic control relay circuit D2, reinforcing portionv of repeater A2 and balancing electrical circuit B2. ln the previousfigures, this transformer was shown wired lin series with this saine bridge arrangement. The balance for the bridge arrangement, on incoming non-amplified speech currents from line H,

is obtained when the relation indicated in `conjunction with Fig. l is satisfied. lo

render inoperative repeater A1 when speech currents are traveling in the direction from line G to line H, contacts 9 controlled by relay @2 are arranged to open circuit the connection between the. energizing portion of repeater A1 and windings 7 and 8 of the transformer associated with line H.'

Fig! 6 shows one-half of the two-way repeater circuit, the omittedpart being entirely symmertical in construction, a modification'of the circuit shown in Fig., 5. rlhe secondary windings of automatic control relay circuit D2 are wired in parallely with each other and with relay C2, instead of being wired in series with .each other and with relay C2, as in- Fig. 5. The. conditions of l balance for the bridge arrangement i peater circuit, the omitted part being enare the same in. this case as indicated in connection with Fig. 4.. Fig. 7 shows one-half of the two-way retirely symmetrical in construction, and is a further-modification in the wiring of the transformer associated with line H, inthat primary windings "and 6 of this transl rangement the primary windings 1 and 2 of circuit D2 may be wiredas one diagonal of the bridge, theother diagonal being 'dif rectly connected to line H. The secondary windings of circuit D2 are wired in series with each other and with relay C2. The secondary windings 7 and 8 of the transformer are wired in series with each other and with the energizing portion of repeater A1. The condition of balance for the bridge is obtained, as is well known, when A where Z1 :impedance of reinforcing portion of e 2 repeater A2. Y Z2 impedance of balancing electrical circuit B2. Z3 :impedance of primary winding 6 when its associated secondary winding is closed through as shown in Fig. 7. Z2=impedance of primary windingl 5 when its associated secondary winding is closed through as shown in Fig. 7.

As a particular case for a condition of balance, we may' choose to make Z1 Z2 Z3 Z,

varrangement of .F|ig.`7, the secondary windings of the transformer associated with line H and with repeater A1, being associated to- L'gether in parallel relation with each other and with repeater A1. The conditions of balance for the bridge are the same as for the arrangement shown in Fig. 7.

Fig. 9 shows another modification of the arrangement of Fig. 7 the Secondary wind-4 ings 3 and 4 of vcircuit D2 being wired 1n y parallel instead of in series, as shown in .Fig 7. The conditions of balance for the bridge are the same as indicated for the arrangement of Fig. 7. Fig.

i l0 is a further modification of the arrangement shown in Fig. 8, the only change being in the secondary windings 3 and 4 of circuit D2 being wired in parallel instead of in series, as shown for the arrangement of'Fig. 8. The conditions of balance for the bridge are the same as for the ar- L rangement of Fig. 7.

Fig 11 isa still further modification of rthe two-way repeater circuit of Fig. 1, the

only change residing in the association of the primary windings 5 and 6 of the transformer associated with line VH, being wired in the bridge arrangement proper, in series with windings l and 2 respectively, of automatic control relay circuit D2. The conditions of balance for the bridge are the same as indicated in connection with .Fig. l, except that the impedance as designated as Z1 and Z2 include, vin addition, the impedance of primary winding 5 (with its associated secondary windings closed through in the manner shown in the drawing) and the impedance of primary winding 6 (with its associated secondary winding closed through as shown in the drawing), respectively. 4

Fig. 12 shows a modification of that shown in Fig. 11, the two secondary windings ref spectively associated with primary windings 5 and' 6 being wired in parallel with each other and with repeater A1, linstead,

v of in series with each other and with repeater A21 The bridge balance relation is the same. in this case as for the arrangement of Fig. 11. y

The arrangement shown on Fig. 13 is a further modification of that shown on Fig. 11, in that windings 3 and 4, of automatic control relay'circuit D2 are wired in parallel instead of in series, as shown for the arrangement of Fig. 11. The general bridge balance condition is somewhat complicated in this case. A specifictcase of balance is secured when balancing repeater B2 is made equal in type and electrical constants to repeater A2, the two primary windings l and 2 are made equal to each other, the two corresponding secondary f 5 and 6 with the bridge, as shown, in-

troduces a dierential effect which is of advantage in making more diicult the establishment of reactive iniuences in theI two-way repeater circuit arrangement. It

will be clear upon examination of these arrangements that while, for instance, n incoming non-amplified speech currents reaching the two-way repeater circuit via line H, the electromotive forces induced in the secondary windings associated with the energizing portion of repeater A, are in the same direction and therefore cumulative in their effect, on the contrary, on amplified prove more advantageous thanothers in.

actual practice, dependingupon the line conditions to be met and the electrical characteristics of the apparatus that may be available for use in given instances. great number of other modificationsy will readily'occur to those who are versed in the yart oftelephony. As, a general indication in this connection, it may be stated that if the combination of the reinforcing portion of one repeater, the balancing-electrical circuit of this repeater and the automatic control relay lcircuit windings associated with the above in a bridge i balance arrangement, is assumed torepresent the transmitter in the usual telephone sub-station set, and the transformer with its primary windings and its secondary windings connected with the energizing portion of the other repeaters is assumed to represent the receiver in the .same sub-station set, then one can combine this transmitter and this receiver in practically as many ways as there arey known or possible type of telephone sub-station circuits. l have only shown some of the most important and characteristic arrangements, embodying the same underlying principle of bridge balance in Fios. l to 13. Extensive departures may thereibre be made along the broad lines indicated,- from the specic arrangements illustrated herein, without. departing from the spirit of the invention.

lt will be noted that in all cases the terminating telephone stations connected with lines G and l-l are normally in full repeating relation in 'either direction and therefore the "two-way repeater circuit is ready for instant service, no prior operation of voice operated or manually operated switching means being required.

l. AIn a telephone system between two terminating stations, the combination with two telephone repeaters at each repeating station, each arranged for one-way` repeating,

but in opposite direction respectively to the telephone systemboth normally iniull retelephone repeater which is arranged for ythe listening station.

said ltelephone system, bothvnormally in flill repeatingrelation to .the said system,` of

voice actuated circuit making and breaking devices and circuit changlng means controlled by the same for rendering inoperative that telephone repeater which is arranged for repeatin in a direction opposite to the direction o transmission from the talking' to the listening station.

2. In a telephone system between two terminating stations, the combination with two repeaters at each repeating station, each I ltwo repeaters atfeach repeating station, each-,- arranged for one-way repeatingbut .in opposite directions respectively toy thel said peating relation to the saidi system, otelectromagnetic relays responsive to voice currents, circuit changing means controlled by the same for rendering inoperative that 10o repeating in a direction opposite to the di rection of transmission 'from the talking to i a. ln a telephone system between' two' terminating stations, the combination with two repeaters at each repeating station, each. arranged' for one-way repeating but-in op posite directions respectively to the said telephone system, both normally in full rei peating relation to the said system, of devices for. convertin and amplifying voice currents into uni irectional currents, direct current relays responsive to thel unidirectional currents thus obtained, circuit' changing means controlled by the Vdirect current relays for rendering inoperative that telephone repeater which is arranged for repeating in a direction opposite to, the direction of transmission 'from i' the talking lto the listening station.

Q5. ln a telephone system between two terminating stations, the combination with. two repeaters at each repeating station, each arranged for one-way repeating but in opvposite directions respectively to the said telephone system, both normally in full repeating relation to the said system, of an faudicn arranged for converting and amplitying voice currents-into unidirectional currents, direct current relays responsive to the unidirectional currents thus obtained, circuit changing means controlled by these direct current relays lfor rendering inoperative that telephone repeater which is arranged for repeating in a direction opposite to the direction of transmissionv from the' telephone system, both normally in full repeating relation to the said system, of two.

bridge arrangements, each bridge arrangement respectively comprising the transmitting circuit of telephone repeater,

the transmitting circuit of a balancing telephone repeater, an automatic controlling circuit with its associated circuit making and breaking device, and line connections to one of the two terminating stations in such a manner that for non-amplified voice currents reaching the bridge over the line connections, the circuit making and breaking device will be in a position of electrical equilibrium in. its corresponding bridge arrangement and willtherefore remain unoperated, while for amplifying outgoing cur-\ rents reaching the same bridge arrangement via the transmitting circuit of the corresponding telephone repeater associated with it, the same circuit making and breaking device will not be in a position of electrical equilibrium and will, when operated, render inoperative, through the circuit changing means it controls, that telephone repeater which is arranged for repeating in a direction opposite to the direction of transmission from the talking to the listening station. f.

7L In a telephone system between two terminating stations, the combination with two repeaters at each repeating station, each arrangedfor one-way repeating but in opposite directions respectively to the said telephone system, both normally in full repeating relation to the said system, of two bridge arrangements each bridge arrangement comprising respectively the transmitting circuit of one telephone re-v peater, the transmitting circuitof a balancing repeater, the primary windings of a transformer with its secondary windings connected to the energizing circuit of the other telephone repeater, an automatic controlling circuit with its associated circuit, making and. breaking device, and line connections to one terminating station in such a manner that for incoming non-amplified currents reaching the bridge arrangement overthe line connections the electromotive forces induced in the transformer secondary windings connected'to the energizing circuit of the repeater last mentioned, will be cumulative in their effect, the circuit making and breaking device being associated in a position of electrical equilibrium in the bridge arrangement remaining unoperated under the same condition; while for amplified voice currents reaching the same bridge arrangement through the transmitting circuit of the iirst mentioned telephone repeater, the electro-motive forces induced in the two transformer secondary windings will be differential in their eflect` thus further reducing any possible tendency toward the establishment of reactive influences in the two-way repeater system, so that the circuit making and breaking device under 'this condition, not being in a position of electrical equilibrium, will, when operated, render inoperative that one of the ltelephone Vrepeaters which is arranged forrepeating in a direction opposite to the direction of transmission from the talking to the listenring station.

ytransmission in the opposite direction;

whereby transmission is effected in 'either direction without initial hiatus or reflexion.

9. Two circuits and two-way repeating apparatus comprising` amplifying means normally conditioned for transmission in either direction between said circuits, and a supplementary set of one-way amplifying means, associated with circuit makingand breaking arrangements, responsive to initial transmission in either direction to discontinue such condition for transmission in the opposite direction; whereby transmission is eected in either direction without initial hiatus or reflexion.

10. Two circuits and two-way repeating appara-tus comprising amplifying means normally conditioned` for transmission in either direction between said circuits and circuit changing means controlled by electromagnetic relays responsive to initial transmission in either direction to discontinue such ycondition for transmission in the opposite direction; whereby transmission is effected in either direction without initial hiatus or reflexion.

l1; Two circuits and two-way repeating apparatus comprising amplifying means normally conditioned for transmission in either direction between said circuits, and

- devices for converting and amplifying voice tion for transmission in the opposite direction; whereby transmission is eected in` either direction without initial hiatus or reiexion i l2. riwo circuits and two-way repeating apparatus comprising amplifying means normally conditioned for transmission in either direction between said circuits, and audion type devices arranged for converting and amplifying voice currents into unidirectional currents, direct current relays responsive to the unidirectional currents thus obtained, circuit changing means, controlled these direct current relays responsive to initial transmission in either direction to discontinue such condition for transmission in the opposite direction; whereby transmission is eiiected without initial hiatus or reiieir'ion.

13., riwo circuits and two-way repeating apparatus comprising amplifying means normally conditioned for transmission in either direction between said circuits, and two brid-ge7 arrangements, each bridge arrangement respectively comprising the transmitting circuit .of one one-way telephone repeater, the transmitting circuit of a balancing telephone repeater, an automatic controlling circuit with its associated circuit making and breaking device, and line connections to one of the two circuits -1n` l sucha manner that for non-amplified 'voice responding telephone repeater associatedwith it, the same circuit making and breaking device will not be in a position of elecn trical equilibrium and will, when operated, in response to initial transmission inthe direction lastL indicated, discontinue such con= dition for transmission in the opposite direc tion; whereby transmission is eected in .either direction without initial hiatus or rcimanes ist. Two circuits and two-way repeating apparatus comprising amplifying means normally conditioned for transmission in either direction between said circuits, and two bridge arrangements, each bridge arrangement vcomprising respectively the transmitting circuit-of one one-way telephone repeater, the transmitting circuit of a balancing repeater, the primary windings of a transformer with its secondary windings connected to the energizing circuit of a second one-way telephone repeater, an automatic controlling circuit with its associated circuit making and breaking device, and line connections to one circuit in such a manner thatior incoming non-amplified currents reaching the bridge arrangement over the line connections, the electromotive forces induced in the transformer secondary windings, connected to the energizing circuit of the repeater last mentioned, will be cumulative in their edect, the circuit making and breaking device, being associated in a position of electrical equilibrium in the bridge arrangement, remaining uno-perated under the same conditiomfwhile for amplified voice currents reaching the same bridge arrangement through the transmitting circuitv of the iirst mentionedtelephone repeater, the electromotive forces induced in the two-way transformer secondary windings will be dierential in their effect, thus further reducing any possible tendency toward the establishment of reactive influencesinthe two-way repeater system, the circuit making and breaking device under this conf dition not being in a position of electrical equilibrium, will, when operated in response to initial transmission in the direction last indicated, discontinue such condition for transmission in the opposite direction; whereby transmission is e'ected in either direction without initial hiatus or reflexion.

in testimony whereof l affix my signature in presence of two witnesses.

MlHRAN M. DOLMAGE.

Witnessesz Y F, J. Fownnn,

MARTHA Kaunas. 

